Process for the production of higher, polyunsaturated carboxylic acid ester and free acids

ABSTRACT

A process for the preparation of higher, polyunsaturated carboxylic acid esters consisting essentially of the steps of reacting a conjugated diolefin with an alkyl ester of methacrylic acid in a ratio of at least 4 mols of diolefin per mol of methacrylic acid ester, in the presence of an organo-metal complex of zero-valent nickel and of an electron donor selected from the group consisting of phosphorous acid triamides, heterocyclic N-bases, aliphatic and aromatic amines, nitriles, sulfides, sulfoxides and triaryl compounds of arsenic and antimony, and recovering said higher, polyunsaturated carboxylic acid ester having more than 19 carbon atoms in the acid moiety. The reaction products are co-oligomerizates of four molecules of conjugated dienes and one molecule of methacrylic acid ester. The ester may be saponified to obtain the free carboxylic acid having more than 19 carbon atoms.

iliiited States Patent Dolir et al.

[ Dec. 17,1974

[ PROCESS FOR THE PRODUCTION OF I HIGHER, POLYUNSATURATED CARBOXYLIC ACID ESTER AND FREE ACIDS [75] Inventors: Manfred Dohr,

Dusseldorf-Holthausen; Helmut Singer, Dusseldorf-Wersten; Wilfried Umbach, Langenfeld, all of Germany [73] Assignee: Henkel and Cie GmbH, Dusseldorf,

Germany [22] Filed: May 25, 1971 [21] Appll No.: 146,780

( fiorgign pplication Priorit y Data UNITED STATES PATENTS 5/l'972 Wilke et al 260/4109 R 1 2/1973 Romanelli 260/4109 R atoms.

Primary Examiner-Lewis Gotts Assistant Examiner-Ethel G. Love Attorney, Agent, or Firm-Hammond & Littell [57] ABSTRACT A process for the preparation of higher, polyunsaturated carboxylic acid esters consisting essentially of the steps of reacting a conjugated diolefin with an alkyl ester of methacrylic acid in a ratio of at least 4 mols of diolefin per mol of methacrylic acid ester, in the presence of an organo-metal complex of zerovalent nickel and of an electron donor selected from the group consisting of phosphorous acid triamides, heterocyclic N-bases, aliphatic and aromatic amines, nitriles, sulfides, sulfoxides and triaryl compounds of arsenic and antimony, and recovering said higher, polyunsaturated carboxylic acid ester having more than 19 carbon atoms in the acid moiety. The reaction products are co-oligomerizates of four molecules of conjugated dienes and one molecule of methacrylic acid ester. The ester may be saponified to obtain the free carboxylic acid having more than 19 carbon 12 Claims, N0 Drawings PROCESS FOR THE PRODUCTION OF HIGHER, POLYUNSATURATED CARBOXYLIC ACID ESTER AND FREE ACIDS THE PRIOR ART It is known from French Pat. No. 1,337,558 that diolefins with conjugated double bonds can be reacted with mono-olefinic compounds in the presence of an organo-metal complex of the iron group, and optionally a substance serving as an electron-donor, to form cooligomers. Suitable catalysts include the zero-valent complexes of the metals of the iron group, which are added either in a pure form to the reaction mixture or are formed in situ by reduction of suitable salts of the said metals with organo-metal compounds or hydrides in the presence of electron donors, or of substances which form structures with isolated pairs of electrons and can act in this form as electron donors. Tertiary amines, alkyl and aryl phosphines, arsines and stibines, phosphines oxides, esters of phosphorous and thiophosphorous acids, triamides of phosphorous acid, esters,

thioethers, sulfoxides, sulfones and mercaptans may be mentioned as electron donors.

According to the above-mentioned French patent, olefins, especially polyolefins, and acetylenic compounds belong to substances which form structures with isolated pairs of electrons and, therefore, may also act as electron donors, while the diene used in the co-oligomerization process may also serve as electron donor in this sense. If the co-oligomerization process is carried out with dienes and mono-olefmic compounds which are activated by a carboxyl group, as for example, derivatives of acrylic and methacrylic acids, then, according to the French patent, a complex compound of zero-valent cobalt is particularly suitable as a catalyst. Complexes of zero-valent nickel are advantageously used for the co-oligomerization reaction of dienes with vinyl ethers or thioethers or olefinic compounds, the double bond of which is activated by an aryl group. The reaction between the diene and derivatives of acrylic and methacrylic acids is carried out by the process of the said French patent in the molar ratio of 1:1, i.e., from butadiene and acrylic esters, for exam ple, mostly esters of 4,6-heptadienoic acid are obtained.

Carboxylic acid esters or carboxylic acids witha relatively high carbon content, namely, reaction products of butadiene and acrylic acid compounds in the molar ratio of 2:1 are obtained according to DDR Pat. No. 54,688 when the reaction is carried out specifically in the presence of an organic complex of zero-valent nickel. According tothis patent, suitable organo-metal complexes of nickel are those which are obtained by reduction of a nickel compound in which the nickel is present in its usual valency, possibly in the presence of electron donors or of substances which are capable of forming structures with isolated pairs of electrons.

Suitable electron donors according to the DDR patent are all those compounds mentioned in the said French patent, thus alkyl and aryl phosphines, alkyl or aryl phosphites, arsines and stibines and the phosphines, phosphites, arsines and stibines named in the French Patent No. 1,337,558, i.e., triphenylphosphine, tri-o-tolylphosphine, tri-a-naphthylphosphine, tris- (trimethylphenyl)-phosphine, triphenylarsine, tri-otolyl-arsine, tri-o-tolylstibine and triphenylstibine, are denoted as particularly advantageous.

In the said DDR patent, it is further stated that the addition of a special electron donor is not necessary, but the diene to be reacted may serve as the electron donor, as in the above-mentioned patent. In the method according to this DDR patent, the reaction between diene and acrylic or methacrylic acid esters is effected exclusively in the molar ratio of 2:1. When an excess of diolefin is used, no further lengthening of the chain of the resultant ester takes place, and on the contrary, the excess diolefin can subsequently be recovered.

Both the DDR patent and the French patent describe the use of electron donors as an alternative measure, while, in addition, no difference is said to exist between the method of action of electron donors which possess isolated pairs of electrons and those which form structures with isolated pairs of electrons.

OBJECTS OF THE INVENTION An object of the present invention is the preration of higher, polyunsaturated carboxylic acid esters and carboxylic acids having at least 19 carbon atoms in the acid moiety in a one step co-oligomerization reaction.

Another object of the present invention is the development of a process for the preparation of higher, polyunsaturated carboxylic acid esters consisting essentially of the steps of reacting a conjugated diolefin with an alkyl ester of methacrylic acid in a ratio of at least 4 mols of diolefin per mol of methacrylic acid ester, in the presence of an organo-metal complex of zerovalent nickel and of an electron donor selected from the group consisting of phosphorous acid triamides, heterocyclic N-bases, aliphatic and aromatic amines, nitriles, sulfides, sulfoxides and triaryl compounds of arsenic and antimony, and recovering said higher, polyunsaturated carboxylic acid ester having more than 19 carbon atoms in the acid moiety.

These and other objects of the invention will become more apparent as the description thereof proceeds.

DESCRIPTION OF THE INVENTION It has now been surprisingly found that in the co-oligomerization of conjugated dienes with methacrylic acid derivatives, the electron donors have an essential influence on the course of the reaction. Namely, if the said compounds are reacted in the presence of organo-metal complexes of zero-valent nickel and specific electron donors, a co-oligomerization between 4 molecules of conjugated diene and one molecule of methacrylic acid derivative can be obtained in a onestage operation. This result, i.e., the possibility of lengthening the chain in a one-stage process, was all the more surprising, since in the DDR patent mentioned above, it is stated that in every case, independent of whether a compound with isolated pairs of electrons is added or whether the diene to be reacted takes over the function of an electron donor, a reaction between the conjugated diene and methacrylic acid derivative only takes place in a 2:1 molar ratio and excess diene can be recovered. Moreover, it is to be taken into consideration that, as is noted in the above-mentioned French patent, electron donors with isolated pairs of electrons may favor a homo-oligomerization of the dienes.

Not all the compounds named in the prior art processes as electron donors have the positive influence described on the course of the reaction. This effect is restricted to compounds from the classes of phosphorous acid triamides, heterocyclic N-bases, aliphatic and aromatic amines, nitriles, sulfides, sulfoxides, and triaryl compounds of arsenic and antimony.

The present invention, therefore, provides a process for the preparation of higher, polyunsaturated carboxylic acid esters and carboxylic acids, comprising reacting a conjugated diolefin with a methacrylic acid ester in a proportion of at least 4 mols of diolefin per mol of methacrylic acid ester, in the presence of an organometal complex of zero-valent nickel and of an electron donor from the class of phosphorous acid triamides, heterocyclic N-bases, aliphatic and aromatic amines, nitriles, sulfides, sulfoxides and triaryl compounds of arsenic and antimony, isolating the ester obtained from the reaction mixture and, if desired, converting said ester into the free carboxylic acid.

Suitable examples of substances from the said classes which can be used as electron donors according to the invention include phosphorous acid triamides such as phosphorous acid trimorpholide, phosphorous acid tri- N-methylanilide, tri-N,N-dialkylamides of phorphorous acid; aliphatic and aromatic amines, which may be primary, secondary, or tertiary, such as hexylamine, dibutylamine, triethylamine, morpholine, N- methylmorpholine, piperidine, triphenylamine, pyridine, the picolines, collidine, quinoline, pyrrole, diphenylamine, benzylamine, dimethylaniline, toluidine; nitriles such as acetonitrile or benzonitrile; aliphatic and aromatic sulfides and sulfoxides such as diethylsulfide, di-tert.-butylsulfide, didodecylsulfide, methyloctylsulfide, diphenylsulfide, cyclohexylphenylsulfide, or dimethyl-sulfoxide; triaryl compounds of arsenic and antimony such as triphenylarsine, trinaphthylansine, tri-o-tolylarsine, triphenylstibine, trinaphthylstibine, tri-o-tolylstibine.

Electron donors from the classes of the heterocyclic N-bases, aliphatic and aromatic amines, sulfides, triarylarsines and triarylstibines are preferred.

For the preparation of the active catalyst solution, about 1 mol of the said electron donor is added per gram atom of nickel.

The preparation of the organo-metal complex of the zero-valent nickel may be carried out in the usual way. Any nickel salt or nickel complex may be used, since insoluble salts in the system also gradually go into solution during the subsequent reduction and give an active catalyst solution. However, anhydrous organic nickel salts, of aliphatic or aromatic carboxylic acids such as, for example, nickel laurate, nickel palmitate or nickel benzoate and chelate complexes, such as nickel-( Il)-acetylacetonate or nickel salicylate, are preferred for the preparation of the catalyst solutions.

For the reduction of the nickel compounds, hydrides and organo-metal derivatives of the elements of Group la, lla, llb, and llla of the Periodic Table, for example, of lithium, sodium, potassium, magnesium, calcium, zinc, boron and aluminum are chiefly suitable. Particularly suitable reducing agents are those of the said types of compounds which enable the operation to be effected in a homogeneous phase, as for example, trialkylaluminum compounds, dialkylaluminum hydrides, trialkylboron compounds, alkylmagnesium bromides and iodides, dialkyl zinc and alkyl lithium compounds.

The relative proportion between the nickel compound to be reduced and the reducing agent is advantageously chosen so that the oxidation equivalent to the reduction equivalent is 1:0.5 to 1:10.

As is generally customary in practice, the complex of active catalyst with zero-valent nickel can advantageously be made in the mixture of compounds which is itself to be reacted. For example, a nickel compound, in which nickel is present in a usual stage of valency, the electron donor and a part of the diene to be reacted are introduced into a solvent and then the reducing agent is added.

Solvents suitable for this reduction process and the subsequent co-oligomerization reaction are those which are inert under the operating conditions. for example, saturated aliphatic hydrocarbons such as hexane, heptane, or octane, saturated cycloaliphatic or aromatic hydrocarbons such as cyclohexane, benzene or toluene, lower alkyl ethers such as diethyl ether or diisopropyl ether, and non-reactive cyclic ethers, such as tetrahydrofuran or dioxan, and also halogenated hydrocarbons, for example, methylene chloride or chlorobenzene.

The relative proportion between the catalyst and the methacrylic acid ester to be reacted is advantageously chosen so that 50 to 200 mols of methacrylic acid ester are used to 1 gram-atom of zero-valent nickel, i.e., the catalyst concentration, based on the sum of the monomers used, amounts to less than 4%. Obviously other amounts of catalyst lie within the scope of the invention, but for reasons of economy, partly owing to the catalyst preparation required, partly owing to the slow course of the reaction, these are not of importance commercially.

Of the methacrylic acid esters to be used as starting substances in the process of the invention, the methyl ester is of primary importance. However, esters of methacrylic acid with other alkanols, as for example, with n-, sec., or tert.-butanol or longer-chain, straightchain and branched-chain alcohols, may be used also in the reaction. The preferred use of the methyl esters is of importance especially when the higher carboxylic acid esters prepared in the process of the invention are to be subsequently saponified to the corresponding acids.

Butadiene, isoprene or 1,3-pentadiene are preferred as the conjugated diolefins to be reacted, butadienel ,3 being the especially preferred starting material.

The process according to the invention may be carried out continuously or discontinuously. The reaction is effected at a temperature of from 20 to C under normal or increased pressure.

It is advisable to carry out the reaction under an atmosphere of a protective gas and to maintain this protective gas atmosphere up to the working up stage of the reaction solution. This protective gas atmosphere is also advantageous in the preparation of the active catalyst solution.

The relative proportions of diolefin and methacrylic acid ester are advantageously chosen so that a small excess of diolefin over the stoichiometrically required amount of 4 mols of diolefin per mol of methacrylate is present. This excess should amount to about 5 to 10% of the theoretical amount of diolefin required.

The separation of the products from the reaction mixture may be effected in the usual way, for example, by fractional distillation. Before the distillation, the active catalyst is suitably destroyed by passing air into the reaction mixture or by addition of a mineral acid.

. .2. EXAMPLES 2 to 8 In an analogous way to that in Example 1, butadiene and methyl methacrylate were reacted in the presence of the following electron donors at various reaction temperatures.

TABLE 1 Reaction Reaction C Q Dist. Ni-(ll) Temp. Time Ester Ester Residue CDT Example Compound Ligand C. hrs. (a) (b) (c) (e) 2 acetylphosphorous acid 20 120 74 94 ca. 5

acetonate trimorpholide 3 do. morpholine 30 48 77 95 4 ca. 4 do. didodecyll 20 78 93 6 ca. 10

sulfide 5 do. triphenylstibine 5O 5 89 95 5 ca 10 6 do. tri hen larsine 50 l 95 9 5 7 ga;l 0 7 palmitate trrphenylstilime 20 24 93 96 4 ca. 5 8 lau111, menylstibine 20 4Q 84 97 3 5 (12) Based on methacrylate used. (b) Based on methacrylate reacted.

ene and 1 mol of methyl methacrylate, a mixturedf at entaene-( 1,6,9,13 ,1 8 )-carboxylic acid-( l0)-methyl ester to be expected on the basis of theoretical considerations. On the other hand, isomerization may again occur if the saponification of the ester obtained is carried out, in which less stable isomers are rearranged into a more stable form.

The esters and acids prepared in the process of the invention are valuable intermediate products fororganic syntheses. They may be converted into the corresponding saturated esters and acids by hydrogenation, and polyfunctional substances may be obtained, by oxidative fission or hydroxylation of the double bonds, which are valuable, for example, as raw materials for polycondensation reactions. Further, as in analogy with drying oils, they may be used in suitable paints.

The present invention will be further described with reference to the following specific examples which are not to be deemed limitative in any manner.

EXAMPLE 1 2 gm (7.8 mMol) of dry nickel (Il) acetylacetonate were dissolved in 100 ml of benzene under an atmosphere of nitrogen. 0.63 ml (7.8 mMol) of pyridine and about 10 gm of butadiene were added thereto. Then 2.2 ml (16 mMol) of triethylaluminum were slowly dropped into the reaction mixture. 39 gm (390 mMol) I ing over at about 135C under a pressure of about 0.1

mm Hg was collected. lt amounted to 1 15 gm and consisted of 96% of a C ester mixture. The yield of C esters, based on methacrylate used, was therefore 89%. The distillation residue obtained was 5%, based on methacrylate used, and the yield, based on methacrylate reacted, was therefore 95%. About 10% of the butadiene used had been trimerized to cyclododecatriene-l ,5,9.

(c) Based on the sum of the monomers used.

(d) C tckididecatruelde- 1,5 ,9, based on IiutadieTt used.

Good yields were obtained too, when butadiene and methyl methacrylate were reacted in the presence of p-toluidine, N,N-diethylaniline, N-methyl piperazine, dimethyl sulfoxide, acetonitrile and N-n-dibutyl amine in a way analogous to that in Example 1.

ire advantages attainable with the invention @6555? given for the synthesis of such carboxylic acids or their derivatives.

THEEEEEEiF TsBEifiE eassaazaaa;mutate; of the practice of the invention. It is to be understood,

however, that other expedients known to those skilled in the art or disclosed herein may be followed without departing from the spirit of the invention or the scope of the appended claims.

We claim:

1. ln the process for the preparation of higher, polyunsaturated carboxylic acid esters comprising the steps of reacting a conjugated diolefin with a lower alkyl methacrylate in a ratio of at least 4 mols of diolefin per mol of methacrylate, in the presence of an organometal complex of zero-valent nickel and of an electron donor, and recovering a higher, polyunsaturated carboxylic acid ester having more than 19 carbon atoms in the acid moiety, the improvement consisting of employing an electron donor selected from the group consisting of phosphorous acid triamides, morpholine, N- methylmorpholine, piperidine, pyridine, the picolines, collidine, quinoline, pyrrole, aliphatic sulfides, triarylarsines and triaryl-stibines.

2. The pr ocess of claim 1 including the further steps of saponifying said higher, polyunsaturated carboxylic acid ester and recovering a higher, polyunsaturated carboxylic acid having more than 19 carbon atoms.

3. The process oi claim 1 wherein said conjugated di olefin is selected from the group consisting of butadiene-1,3, isoprene and pentadiene-l,3.

4. The process of claim 3 wherein said conjugated diolefin is butadiene-1,3.

5. The process of claim 1 wherein said lower alkyl methacrylate is methyl methacrylate.

6. The process of claim 1 wherein said reaction is effected at a temperature between about C to 150C.

7. The process of claim 1 wherein said reaction is conducted under a protective gas atmosphere.

8. The process of claim 1 wherein an inert organic solvent is present.

9. The process of claim 1 wherein said organo-metal complex of zero-valent nickel is formed in situ in the presence of part of said conjugated diene and said electron donor by the reduction of an anhydrous organodonor is triaryl-stibine. 

1. IN THE PROCESS FOR THE PREPARATION OF HIGHER, POLYUNSATURATED CARBOXYLIC ACID ESTERS COMPRISING THE STEPS OF REACTING A CONJUGATED DIOLEFIN WITH A LOWE ALKYL METHACRYLATE, IN THE OF AT LEAST 4 MOLS OF DIOLEFIN PER MOL OF METHACRYLATE, IN THE PRESENCE OF AN ORGANO-METAL COMPLEX OF ZERO-VALENT NICKEL AND OF AN ELECTRON DONOR, AND FECIVEING A HIGHER, POLYUNSATURATED CARBOXYLIC ACID ASTER HAVING MORE THAN 19 CARBON ATOMS IN THE ACID MOIETY, THE IMPROVEMMENT COMPRISES OF EMPOLYING AN ELECTRON DONOR SELECTED FROM THE GROUP CONSISTING OF PHOSPHOROUS ACID TRIMIDES, MORPHOLINE, N-METHYLMORPHOLINE PIPERADINE, PYRIDINE, THE PICOLINS, COLLIDINE, QUINOLINE, PYRROLE, ALIPHATIC SULFIDES, TRIAYL-ARSINES AND TRIARYL-STIBINES.
 2. The process of claim 1 including the further steps of saponifying said higher, polyunsaturated carboxylic acid ester and recovering a higher, polyunsaturated carboxylic acid having more than 19 carbon atoms.
 3. The process of claim 1 wherein said conjugated diolefin is selected from the group consisting of butadiene-1,3, isoprene and pentadiene-1,3.
 4. The process of claim 3 wherein said conjugated diolefin is butadiene-1,3.
 5. The process of claim 1 wherein said lower alkyl methacrylate is methyl methacrylate.
 6. The process of claim 1 wherein said reaction is effected at a temperature between about 20*C to 150*C.
 7. The process of claim 1 wherein said reaction is conducted under a protective gas atmosphere.
 8. The process of claim 1 wherein an inert organic solvent is present.
 9. The process of claim 1 wherein said organo-metal complex of zero-valent nickel is formed in situ in the presence of part of said conjugated diene and said electron donor by the reduction of an anhydrous organo-nickel compound by a compound selected from the group consisting of a hydride and an organo-metal compound of metals selected from the group consisting of lithium, sodium, potassium, magnesium, calcium, zinc, boron and aluminum.
 10. The process of claim 1, wherein said electron donor is a phosphorous acid triamide.
 11. The process of claim 1 wherein said electron donor is a triaryl arsine.
 12. The process of claim 1 wherein said electron donor is triaryl-stibine. 